Small sprocket won't turn

motorbikerider · #1 (**permalink**) 10-31-2009, 04:05 AM

I just completed my first build, however the small sprocket is seized up for some reason. I haven't put fuel in it or tried to test drive it. I tried walking it forward and the back tire drug and eventually the chain came off. The instruction manual says you should be able to turn the sprocket by hand easily and if it is stuck try wiggling it back and forth gently. That didn't work, I'm sure there is someone on here that has a good answer for me, i've already learned alot on here.

Appreciate it,
Motorbikerider

**BarelyAWake** · #2 (**permalink**) 10-31-2009, 04:57 AM

Well - first off the "manual" is full of **** - you'd have to have thumbs of iron to turn that sprocket by hand on most of these. I've almost 1000 miles on mine and it's still a struggle.

First though - if your chain came off you have other problems, check your rear and front sprocket alignments and also if you have any offset or "wobble" in the rear sprocket - the rubber mounts are a pain to get just right. Another important one is to make sure your roller/tensioner is not only mounted properly and taking up all but about 1/2" of slack - but you'll also need to put it in a vice and bend it just a little so it's in line with the chain. If ya just bolted it on - it's lined up with the chainstay and not the chain itself.

Once that's all sorted, you can pull the spark plug out to eliminate compression resistance, then try turning the engine over again. You'll still need to be on the bike as it may skid anyway without any weight on it.

Some of these motors are a lil stuck when you get 'em - most are fine, they've just not been broken in yet and things are a lil tight.

Good luck man - yer gonna love it when you get it done

scott83 · #3 (**permalink**) 10-31-2009, 08:01 AM

My first build had the same problem. I pulled in the clutch lever and could not turn the sprocket ( with a large flat screwdriver ) without the engine trying to start. Mine was a clutch problem (since the motor should not turn over with the clutch lever pulled in...the clutch obviously wasnt working properly ) I took the 5 screws out holding the clutch cover on (opposite side from the chain drive) soon as it was off I saw fibers hanging out from between the clutch plate and the large ring gear. 1st remove the small set screw from the middle of the clutch pressure plate. 2nd pull the clutch lever in so youll see the clutch working, with the clutch pulled in you can loosen the center flat star shapen adjusting nut that the set screw you removed earlier was stopping from turning, adjusting might fix youre problem....unless it is like mine was....if so remove the center adjusting nut pull off the pressure plate and look for fibers or junk on the 15 rubber and fiber clutch pads...I had to trim fibers off of 2 pads myself ....reassemble check clutch adjustment replace the set screw and cover....and have fun. Oh yeah after the clutch was properly working I was able to turn the small sprocket with my fingers with some effort ...but turning it with the screwdriver was a breeze

Just saw norms excelent article with pics and diagrams explaining the whole process in the sticky posts above youre post...good luck.

sojudave · #4 (**permalink**) 10-31-2009, 10:27 AM

First thing. Were you engaging your clutch by squeezing the lever? If so, you might want to start by tightening up your clutch cable. You can do this by loosening the scew on the clutch arm that is on your engine. The with a pair of pliers, tug on the cable and have a buddy push the arm a little tighter than before then tighten it all down again. Keep doing this until you can free up the rear wheel by squeezing your clutch lever.

moun10biker · #5 (**permalink**) 10-31-2009, 11:14 AM

Make sure at the end of the clutch pin, the ball bearing is still there. Also, like sojudave said, the clutch may not be pulling the cable hard enough. I have that same problem, and I got my mom to help hold some pliers while I pushed the clutch arm in and screw the little brass thing on. I had to push in in alot, so the clutch would pull the arm in enough for it to go in neutral. My thumbs were about to fall out! Also, use some good moly grease to lube everything up in there. I like valvoline multipurpose grease at Schucks.

gubba · #6 (**permalink**) 10-31-2009, 03:05 PM

i install and service these kits into customers bike foe a side living.
recently i installed a 80cc and you could not turn the pedals, with/without the clutch in.
finally i removed the clutch hub from the motor and it was froze tight, you could not turn the inner hub even with a breaker bar.
i sent the complete hub to jim at CREATIVE ENGINEERING (the manic mechanic ad on the left side) and he replaced the cheap chinese berrings with hard steen ones.
i reinstalled it and it runs sweet.

stay dry
gubba